!      VugUBl     1.     HMD. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

I'.i  1:1  \l    OF  PLANT  INDUSTRY  -Circular  No.  68. 
B.  T.  GALLOWAY,  Chlel  i 


EXPERIMENTS  ON  THE  APPLE  WITH   SOME 
NEW  AND  LITTLE-KNOWN  FUNGICIDES. 


BY 


M.  B.  WATTE, 
Pathologist  in  Charge  of  Frutt-Dis]  w  Investigations. 


372W-Clr.  »-10 1 


WAlMINOTOt    :  GOVERNMENT  PHtHTISO  OFFICE   !   1»tO 


" 

BUREAU  OF  PLANT  INDUSTRY. 


Chief  of  Bureau,  Beverly  T.  Galloway. 
Assistant  Chief  of  Bureau,  G.  Harold  Powell. 
Editor.  J.  E.  Rockwell. 
Chiif  Clerk,  James  E.  Jones. 
[Cir.  58] 
2 


Ii    F    i 


EXPERIMENTS  ON  THE  APPLE  WITH  SOME  NEW 
AND  LITTLE-KNOWN  FUNGICIDES.0 


INTRODUCTION. 

Km-  many  ye  Bordeaux  mixture  has  been  the  leading  fungicide 
for  summer  treatment  of  the  apple,  the  pear,  and  certain  other  fruits. 
Ii  was  soon  found,  however,  thai  ii  could  qoI  !»«■  used  on  the  peach 
and  the  Japanese  plum,  as  it  caused  serious  shot-holing  of  the  Leaves 
and  summer  or  premature  defoliation  of  these  trees. 

Injury  caused  by  Bordeaux  mixture  ha-~  not  been  confined  wholly 
to  the  peach.  There  has  been  an  increasing  Dumber  of  complaints 
during  the  last  few  years  about  russeting  or  spray  injury  to  the  fruit 
of  the  apple  due  to  this  mixture.  Not  onl\  the  fruit  is  injured,  but 
trouble  has  occurred  on  the  foliage  also,  in  the  form  of  dead  spots, 
minute  reddish  flecks,  yellow  ing,  and.  w  hat  is  b1  ill  more  serious,  defo- 
liation. 

The  fruit  russeting  has  been  pretty  clearly  recognized  as  du< 
the  spraying  with  copper.     Minute  reddish   flecks  <»u  the  fruit  and 
particularly  the  spotting  and  flecking  of  the  foliage  have  been  I 
clearly  attributed  to  copper  poison,  some  patho  and  fruit  grow- 

understanding  it,  while  others  have  mi-taken  the  copper  injury 
for  disease.  While  Bordeaux  mixture  has  been  the  most  useful 
and  successful  fungicide  that  has  ever  been  discovered,  it  has  been 
open  to  tins  Berious  objection,  which  for  some  unknown  reason  has 

increased  in  recent  year-. 

"Thi-  [>:»!>•  r  i-  i  preliminary  r.-j  Eperimenta  on  the  apple  with  nine 

different  fungicides  cirri'  I  >>n  in  Virginia  during  thi  Imong  th 

an  iron  sulphid  and  a  copper  Bulphid  were  sufficiently  different  from  those  previously 
I  to  be  regarded  as  new.  The  experiments  were  conducted  in  connection  with  a 
study  ol  the  russet  problem  oar  spray  injury  to  apples  caused  t>>  Bordeaux  mixture.  If 
the  ri^alt.-i  can  be  tvii.'  1  up  'ii  they  will  help  materially  in  soh  ing  tl.i-  problem.  While 
the  reeultB  with  the  new  mixtures  were  favorable,  the  author  very  properly  doi 

mmend  them  for  general  use,  but  only  for  trial  in  an  <  xperimental  way.    The  inter- 
d  fungicides  and  in  spraying  fruit  it  and  the  demand  on  the  part  of 

fruit  growers  for  prompt  information  is  so  insistent  that  it  seems  desirable  to  give 
these  results  before  they  can  l><-  further  tested.  — G.  11.  Powzu  ,  Acting  I  kief 
[Cta  3 


4        EXPERIMENTS  ON  THE  APPLE  WITH  SOME  NEW   FUNGICIDES. 

The  matter  became  so  serious  that  a  special  investigation  was 
started,  and  a  scries  of  field  experiments  was  undertaken  at  Winches- 
ter, Ya.,  during  the  season  of  1909  for  the  purpose  of  solving,  if 
possible,  this  russeting  or  spray-injury  problem.  These  experiments 
consisted  in  testing,  by  spraying,  nine  different  fungicides.  In  the 
test  were  included  standard  Bordeaux  mixture,  self -boiled  lime- 
sulphur,  and  various  modifications  of  Bordeaux  mixture.  These 
were  the  most  promising  fungicides  known  to  the  writer.  Included 
in  the  test  were  two  new  fungicides,  a  new  form  of  copper  sulphid 
and  a  new  iron  sulphid,  that  were  tested  for  the  first  time.  To  our 
surprise  these  two  new  mixtures  proved  remarkably  good  and  among 
the  best.  The  new  iron  sulphid,  particularly,  may  have  a  promising 
future. 

A  full  report  on  the  experiments  just  mentioned,  with  illustrations 
and  with  a  discussion  of  the  russet  problem,  is  in  preparation,  but 
as  the  interest  in  spraying  and  spray  materials  is  so  great  and  the  full 
report  may  not  be  ready  in  time  for  the  spra}*ing  season,  tins  pre- 
liminary report  is  given  out,  particularly  for  the  purpose  of  describing 
the  two  new  fungicides  and  the  results  obtained  with  them. 

Mr.  F.  V.  Rand,  Scientific  Assistant,  aided  in  carrying  on  the 
spraying  work  and  in  taking  notes  of  the  results. 

PLAN   OF  THE    EXPERIMENT. 
SERIES    I. 

The  main  experiment  was  carried  out  on  the  place  of  Mr.  S.  L. 
Lupton,  at  Winchester,  Ya.  The  most  complete  series,  containing 
eleven  plats,  known  as  Series  I,  was  on  Mr.  Lupton 's  home  farm. 

The  following  shows  the  formulas  of  the  fungicides  used  on  the 

various  plats: 

Plat  1. — Control,  unsprayed. 

Plat  2. — Standard  Bordeaux  mixture  (3-3-50). 

Plat  3. — Iron  Bordeaux  mixture  (3-3-50  plus  2  pounds  of  copperas,  or  iron  sulphate). 

Plat  4. — Standard  Bordeaux  mixture  plus  gypsum  (3-3-50  plus  3  pounds  of  gypsum). 

Pint  5. — Neutral  Bordeaux  mixture  (3-X-50,  X  equaling  lime  added  until  the 
neutral  poiut  as  shown  by  the  litmus  test  is  reached). 

Plat  6.— Self-boiled  lime-sulphur  (10-10-50). 

Plat  7. — Copper-sulphid  mixture  No.  1  (self-boiled  lime-sulphur,  10-10-50,  plus 
2  pounds  of  copper  sulphate). 

Plat  8. — Copper-sulphid  mixture  No.  2  (Bordeaux  mixture,  3-3-50,  plus  1  gallon 
of  commercial  lime-sulphur  solution). 

Plat  9. — Iron-sulphid  mixture  (self-boiled  lime-eulphur,  10-10-50,  plus  3  pounds 
of  copperas  or  iron  sulphate). 

Plat  10. — Arsenate  of  lead  (used  alone),  2  pounds  to  50  gallons. 

Plat  11. — Control,  unsprayed. 

To  each  of  these  fungicides  arsenate  of  lead  in  the  form  of  the  ordinary  paste  was 
added  at  the  rate  of  2  pounds  per  50  gallons  of  spray  mixture. 
[Cir.  58] 


EXPERIMENTS  ON    mm     \rn.'     nun   SOME    NEW    FUNGICIDE8.        ;> 

The  orchard  in  which  this  Beries  of  plats  was  located  was  planted 
in  strips  of  four  rows  each  of  Ben  1  >ai  is,  Yd  low  Newtown,*  and  fork 
[mperial  trees.  Bach  plaj  consisted  of  a  row  running  across  the 
varieties  so  as  to  include  I  Ben  Davis,  I  fellow  Newtown,  and  2  fork 
[mperial  trees.  The  Hen  D:i\  is  was  known  t"  !>«•  \ erj  badly  affected 
l>\  russeting,  the  Yellow  Newtown  moderately  affected,  and  the  fork 
[mperial  aotabrj  immune  to  this  tyj f  injury. 

-i  an  -  ii. 

The  blossoms  being  somewhat  scant  on  the  block  on  the  home  farm 
and  the  trees  do!  especially  strong  and  productive,  a  duplicate  Beries 
(Scrit--,  III  was  arranged  in  Mr.  Lupton's  Baker  orchard  in  a  block 
consisting  entirely  of  Ben  Davis  tree-.  This  second  Beries  was  car- 
ried out  on  the  same  plan,  with  the  exception  of  plats  8  and  9,  which 
were  left  out.  as  they  were  not  considered  especiallj  promising  when 
1 1 1 i~i  series  \\  as  started.  The  t  rees  in  both  blocks  w  ere  l  I  years  of  i 
Some  t  rees  were  missing  in  the  plats  of  Series  I  Ma  eh  plat  in  Series 
1 1  consisted  of  l  Hen  I )avis  t rees  rather  heavily  fruited,  each  carrying 
several  barrels  of  apples. 

eh  rn. i:\m.vi  \i.  bi  ansa. 

\  supplemental  Beries,  in  which  the  self-boiled  lime-sulphur  and 
the  copper-sulphid  mixture  were  \]-ri\  on  the  Hen  Davis  variety, 
was  carried  out  in  the  orchard  of  Mr.  Stewart  Bell.  Another  supple- 
mental test  on  the  York  [mperial  anil  the  Hen  Davis  was  carried 
out  in  the  orchard  of  Mr.  Phil  Gold,  comparing  self-boiled  lime- 
sulphur  and  standard  Bordeaux  mixture,  the  dates  of  treatment 
being  approximately  the  Same  a-  in  Series  I  and  1 1. 

DATES   OF    APPLICATION   OF   THE    SPRAYS. 

The  sprays  were  applied  with  an  ordinary  hand  barrel  pump,  a  noz- 
zle with  a  fairly  small  opening  which  produced  a  tolerably  fine  mist- 
like spray  being  used.  The  first  application  Was  made  May  1  I  and  1  _'. 
Bhortly  after  the  petals  had  fallen,  while  the  calyxes  Were  still  open. 

The  second  application  was  made  June  1 1  and  12,  jus!  a  month  later; 

in  fact,  a  week  later  than  was  intended.      The  third  application  •■ 
made  .'illy  10. 

The  first  application  was  made  in  time  to  id]  the  calyx  cups  with 
the  arsenate  and  in  good  season  to  catch  early  infections  of  cedar  rust 
and  leaf-blight.  This  is  usually  also  a  timely  application  to  protect 
from  apple  scab,  though  not  thoroughly  reliable  in  a  hail  season.     It 

oThi.<  variety  ia  known  also  as  Newtown  Pippin,  and  in  Virginia  as  Albemarle  Pi ]>i>in, 
or  simply  Pippin. 
Kir.  58] 


b        EXPERIMENTS  ON   THE   APPLE  WITH   SOME   NEW   FUNGICIDES. 

represents  the  time  of  the  second  treatment  for  that  disease,  the  first 
one  being  made  just  before  the  petals  open. 

The  second  application,  on  June  11,  while  it  answered  very  well 
under  the  conditions  at  Winchester,  might  be  regarded  as  a  little 
late.  June  1  to  5  would  be  a  better  time  for  this  application  in  ordi- 
nary years.  This  application  is  intended  to  catch  the  codling  moth 
at  the  time  of  hatching  and  feeding,  and  as  the  trees  are  just  in  full 
leaf  it  is  the  best  single  treatment  for  apple  leaf-blight  or  leaf-spot, 
though  a  little  late  for  the  cedar-rust  fungus. 

The  third  application  was  made  on  Jul}'  19.  This  was  also  perhaps 
a  week  too  late,  but  is  an  excellent  date  for  the  last  summer  treatment 
for  fruit  spots  and  leaf  diseases  and  is  timely  for  the  second  brood  of 
codling  moths  and  for  the  lesser  apple  worm.  The  spray  applied  at 
this  time  is  expected  to  cling  to  the  fruit  and  foliage  and  protect  them 
from  fungous  attacks  for  the  rest  of  the  season.  Only  under  un- 
favorable conditions  and  on  varieties  subject  to  attack  by  the  bitter- 
rot  fungus  are  later  treatments  necessary.  In  unfavorable  seasons 
one  or,  perhaps,  two  additional  treatments  might  be  necessary  for  the 
bitter-rot. 

The  dates  specified  were  arranged  in  conference  with  Prof.  A.  L. 
Quaintance,  of  the  Bureau  of  Entomology,  who  is  responsible  for  such 
matters  as  relate  to  insects  and  insecticides  in  this  circular. 

PREPARATION   OF   THE    SPRAYS. 

Plat  2,  standard  Bordeaux  mixture,  3-3-50  formula. — Heretofore, 
stronger  mixtures  of  bluestone  and  lime  have  been  regarded  as  the 
standard,  but  for  the  purpose  of  this  experiment  the  3-3-50  Bordeaux 
mixture  was  used  as  the  standard.  It  was  made  up  in  the  ordinary 
way,  a  stock  solution  of  bluestone  and  a  stock  mixture  of  slaked-  lime 
paste  being  used.  The  materials  were  diluted  and  run  together  by 
gravity  into  a  tank. 

To  this  mixture,  as  to  all  the  other  fungicides,  2  pounds  of  arsenate 
of  lead  mixed  up  to  a  cream  and  passed  through  a  sieve  were  added  as 
the  last  step  before  filling  into  the  spray  tank.  The  result  was  a 
rather  light  sky-blue  mixture,  which  stood  up  very  well  without 
settling. 

Plat  3,  iron  Bordeaux  mixture. — On  plat  3  was  used  standard  3-3-50 
Bordeaux  mixture,  as  on  plat  2,  to  which  3  pounds  of  dissolved  iron 
sulphate  diluted  in  about  6  gallons  of  water  were  added.  Space  was 
left  in  pouring  the  bluestone  and  lime  together  to  allow  for  the  addi- 
tion of  the  diluted  iron  sulphate.     The  iron  produced  a  brown  color." 

«  The  addition  of  iron  sulphate  to  Bordeaux  mixture  as  a  sticker  has  been  recom- 
mended by  Prof.  A.  D.  Selby,  of  Ohio.      • 
[fir.  58] 


EXPERIMENTS  ON     Mil     \  ITI.I     u  I  M I    BOMB    NEW    FUNGICIDES,        7 

Pint  ;,  gypsum  Bordeaux  mixture.  This  was  prepared  in  the  same 
manner  as  the  spray  for  plat  •">.  •">  3  50  Bordeaux  mixture  being  made 
op  and  ■!  pounds  of  gypsum  mixed  \\  it  li  6  or  8  gallons  of  water  added 
in  filling  the  barrel.     No  change  in  color  resulted. 

Plat  .I,  in  utral  Bordeaux  mixturt .  This  spraj  w  as  made  in  the  same 
manner  a  standard  Bordeaux  mixture,  except  that  a  verj  small 
quantity  of  lime  was  used  and  an  excess  of  bluestone  in  running  the 

materials  into  the  barrel.     With  the  excess  of  bluest •,  blue  litmus 

paper  is  turned  red.     Lime  was  cautiously  added  until  do  marked 
change  was  produced  in  either  the  blue  or  the  red  litmus  paper. 

I'lut  6,  self-boUed  lime-sulphur.  In  these  experiments,  the  rather 
Btrong  lo  10  50  self-boiled  lime-sulphur  was  purposely  used,  bo 
that  if  spraj  injury  resulted  it  would  occur  at  its  worst.  In  mak- 
ing up  the  in>n  sulphid  and  the  copper  sulphid  mixtures,  therefore, 
the  same  formula  of  10  10  50  was  used.  In  commercial  work,  how- 
ever, the  8  s  50  formula  should  be  used. 

Briefly  stated,  this  mixture  is  made  up  as  follows: 

In  a  barrel  holding  50  gallons  place  8  pounds  of  good  stone  lime. 
P  it  over  this  enough  wafer  to  nearly  cover  it.  As  the  lime  begins 
to  slake,  dump  in  the  sulphur.  This  Bhould  preferably  be  run 
through  a  screen,  to  break  up  lumps,  and  mixed  with  water  to  the 
consistency  of  a  slush.  Stir  the  sulphur  into  the  slaking  lime 
with  a  strong  paddle  and  add  water  enough  to  keep  the  lime  from 
burning  and  to  keep  the  mixture  in  a  slushy  condition.  The  stirring 
should  continue  occasionally  until  the  greater  portion  of  the  lime  is 
slaked  into  a  cream  or  paste.  Meantime  the  barrel  Bhould  he  cov- 
ered with  burlap  sacks  or  a  piece  of  old  carpet  or  otherwise  pro- 
tected to  retain  the  heat.  At  tin1  end  of  fifteen  or  twenty  mini. 
the  lime  will  be  found  to  be  thoroughly  slaked  and  the  sulphur  partly 
combined  with  it.  ( lonsiderable  brown  discolorat  ion  shows  the  extent 
of  the  chemical  combination.  The  mixture  is  then  diluted,  first 
with  a  small  quantity  of  water  stirred  in  with  a  paddle  and  then 
sufficiently  to  fill  the  barrel  to  the  50-gallon  mark.  Space  is  left 
before  finishing  to  add  the  2  pounds  of  arsenate  of  lead,  stirred  in,  in 
the  form  of  milk,  in  2  or  •">  gallons  of  water. 

Pitt  7.  copper-sulphid  mixture,  No.  1. — To  make  this  spray  tin' 
self-boiled  lime-sulphur,  already  described  (10—10-50),  was  used  as  a 
basis.  Space  was  left  to  add  2  pounds  <>f  copper  sulphate  in  solu- 
tion, diluted  with  about  6  or  s  gallons  of  water.  This  turned  the 
mass  a  decidedly  bright  reddish  brown  color  as  it  was  stirred 
into  the  mixture.  On  the  addition  of  2  pounds  <>f  arsenate  of  lead, 
previously  mixed  with  water  into  a  milk,  no  additional  change  m 
color  was  apparent.     This  may  have  been  due  to  inability  to  detect 

h'ir 


8         EXPERIMENTS  ON   THE   APPLE   WITH   SOME    NEW    FUNGICIDES. 

any  further  color  change  on  account  of  the  dark  color  of  the  copper 
sulphid.  This  mixture  is  somewhat  parallel  in  a  general  way  as  a 
summer  spray  with  the  Oregon  wash  (so  called)  as  a  winter  spray. 

The  Oregon  wash  is  made  by  adding  bluestone  solution  to  the 
strong  home-boiled  lime-sulphur  mixture  and  is  used  only  for  a 
winter  wash.  It  is  more  nearly  like  the  copper-sulphid  mixture  tried 
by  W.  H.  Volck,  County  Entomologist,  Watsonville,  Cal.,  and  de- 
scribed in  a  report  on  powdery  mildew  of  the  apple. a  The  copper 
sulphid  used  by  Volck  was  made  by  adding  bluestone  to  the  commer- 
cial lime-sulphur  solution.  This  resulted  in  a  strong  mixture  which 
could  not  be  used  at  once  but,  according  to  Mr.  Volck,  on  decanting 
and  washing,  it  could  be  sprayed  on  the  apple  trees.  The  washing, 
however,  required  two  or  three  days. 

The  new  feature  in  making  the  copper-sulphid  mixture  is  the  use 
of  the  self-boiled  lime-sulphur  as  a  basis.  This  is  so  mild  in  its  com- 
position as  to  permit  the  immediate  use  of  the  mixture  without 
washing. 

Plat  8,  copper-sulphid  mixture,  Aro.  2. — This  is  a  copper-sulphid 
mixture  made  by  using  the  standard  Bordeaux  mixture  (3-3-50) 
as  a  basis  and  adding  a  gallon  of  the  strong  commercial  lime-sulphur 
stock  solution  diluted  in  2  or  3  gallons  of  water  after  the  bluestone 
and  lime  have  been  combined.  This  is  also  a  mixture  somewhat 
similar  to  that  used  by  Volck,a  but  is  different  in  that  it  has  an  excess 
of  lime,  a  part  of  which  is  combined  with  bluestone  before  add- 
ing the  sulphur.  On  account  of  wanting  to  use  this  mixture  at  once 
without  washing  and  being  afraid  of  its  caustic  action,  only  1  gallon 
of  the  lime-sulphur  solution  per  50  gallons  was  used,  though  1£ 
gallons  can  be  used  in  water  alone.  The  mixture  gave  the  light 
reddish  brown  color  characteristic  of  the  copper  sulphid.  It  was 
applied  without  washing  or  decanting. 

Plat  9,  iron-sulphid  mixture. — The  new  form  of  iron-sulphid  mix- 
ture is  made  by  using  the  self-boiled  lime-sulphur  (10-10-50)  as  a 
basis.  A  barrel  of  the  self-boiled  lime-sulphur  is  prepared  as  already 
described  and  diluted  to  about  40  gallons.  Iron  sulphate  (copperas), 
3  pounds,  dissolved  in  6  to  8  gallons  of  water,  is  then  added.  The 
iron  sulphate  might  perhaps  be  still  further  diluted  to  advantage. 
When  this  is  added  and  stirred  into  the  barrel  the  mixture  turns 
inky  black.     Then  2  pounds  of  arsenate  of  lead  are  added,  as  before. 

The  iron  sulphate  can  be  weighed  out  and  dissolved  in  a  large 
bucket  by  stirring,  or,  better,  it  can  be  prepared  in  a  stock  solution, 

"  ''The  Apple  Powdery  Mildew  in  the  Pajaro  Valley,"  Special  Bulletin  No.  1,  by 
W.  H.  Volck,  County  Entomologist  for  Monterey  and  Santa  Cruz  counties.     Watson- 
ville,  Cal.,  May,  1909. 
[Cir.  58] 


EXPERIMENTS  OH    lift     \i  i'l  I     WITH  80M1     MEM     FUNGICIDES.        •) 

M  i-  customar)  with  < ■» >| » [ »«■  r  sulphate,  at  the  rate  (.f  i  pound  to  the 
gallon  (if  u ater 

The  new  feature  in  this  iron  sulphid,  as  in  i h«-  new  copper  sulphid, 
consists  in  using  the  Belf-boiled  lime-sulphur  as  a  basis  instead  "f  the 
concentrated  lime-sulphur  solution.  Volck,  in  the  bulletin  already 
cited,  described  an  iron  sulphid  like  his  copper  Bulphid,  made  by 
adding  iron  Bulphate  to  the  lime-sulphur  solution.  I'm  this,  like  the 
copper  sulphid,  required  decanting  and  washing  for  two  or  three  da 
to  render  ii  suitable  for  use  upon  foliage.  Ii  was  decided  to  use  the 
Belf-boiled  lime-sulphur  in  the  hope  of  getting  a  more  harmless  mixture 
which  could  be  made  up  and  used  at  once,  as  the  washing  was  not 
considered  practicable  or  was,  at  least,  \  en  objectionable.  The  plan 
succeeded  in  that  the  mixture  was  quite  harmless.  The  inky  black 
mixture  was  apparently  colloidal  or  somewhal  gelatinous  in  texture 
and  after  drying  on  the  trees  turned  a  dark  date  color.  In  a  few 
day-  tin-  oxidized  t<>  a  reddish  brown  color,  which  remained  constant. 

RESULTS. 

Apple  leaf-spot  and  the  cedar-rust  fungus  began  to  appear  on  the 
leave-  of  the  unsprayed  trees  at  the  date  of  the  second  treatment. 
Furthermore,  a  rather  vicious  spray  injurj  of  the  foliage  and  ru<- 
seting  of  the  fruit  began  to  appear  on  the  Bordeaux-mixture  plats 
at  the  same  time.  The  taking  of  note-  of  the  results  was  begun, 
therefore,  at  that  time  and  continued  at  frequent  intervals  through- 
out the  season.  The  fruit  was  Borted  and  weighed  at  picking  time 
and  a  -ample  ho.x  of  apple-  from  each  important  plat  was  packed 
and  placed  in  cold  Storage.  Careful  note-  on  the  condition  of  the 
fruit  from  the  different  plats  were  taken  at  picking  time  and  again 
at  the  time  the  fruit  was  removed  from  cold  storage,  when  it  was 
placed  on  exhibition  before  the  Virginia  Mate  Horticultural  Society, 
January  5  to  7.  The  detail-  as  to  the  differences  between  these 
plats  and  between  the  resulting  fruit-  may  be  described  more  fully 
in  a  later  publication.  For  the  present  purpose,  however,  the  fol- 
lowing important  results  may  he  stated: 

SERIES    I. 

All  the  fungicides  protected  the  tree<  almost  completely  from 
fungous  diseases,  and  since  the  arsenate  of  lead  was  combined  with 
them  they  also  controlled  the  codling  moth  and  other  insect  pests. 
It  therefore  became  a  question,  a-  was  intended  from  the  -tart.  <>f 
determining  the  merit-  of  the  different  mixtures  largely  through 
their  effect  in  producing  -pray  injury. 
97294°-  Cir.  58  -10 2 


10        EXPERIMENTS  ON   THE  APPLE  WITH  SOME   NEW   FUNGICIDES. 

Plat  1,  control. — The  extent  of  damage  to  the  leaves  of  this  plat 
by  fungous  diseases  was  estimated  at  60  per  cent  on  September  21, 
a  week  before  picking  time,  and  the  damage  to  fruit  from  fungous 
fruit  spots  and  insect  injuries  was  estimated  at  90  per  cent  on  the 
Ben  Davis  (of  which  slightly  more  than  half  was  due  to  the  codling 
moth),  20  per  cent  on  the  Yellow  Newtown  (of  which  three-fifths 
was  caused  by  the  codling  moth),  and  10  per  cent  on  the  York 
Imperial  (of  which  three-tenths  was  codling-moth  injury). 

Plat  2,  standard  Bordeaux  mixture. — The  fungous  damage  to  the 
leaves  in  this  plat  was  estimated  on  September  21  at  1  per  cent  on 
the  Ben  Davis  trees,  and  the  fungous  and  insect  damage  to  the  fruit 
at  2  per  cent.  This  was  merely  nominal.  On  the  other  hand,  the 
injury  to  the  leaves  by  copper  poisoning  on  the  date  mentioned  was 
estimated  at  30  per  cent,  and  the  fruit  russeting  at  GO  per  cent. 
This  was  the  greatest  percentage  of  damage  to  any  of  the  fruit  by 
any  of  the  sprays.  The  only  damage  of  greater  extent  was  that  to 
the  Yellow  Newtown  leaves,  which  were  marked  80  per  cent  injured. 
The  reverse  was  true  of  the  Yellow  Newtown  fruit,  only  30  per  cent 
of  which  was  injured.  About  25  per  cent  of  the  York  Imperial 
leaves  was  injured,  while  only  3  per  cent  of  the  fruit  was  injured 
by  spray  russeting. 

Since  the  fruit  of  the  Ben  Davis  was  very  susceptible  to  spray 
injury  throughout,  the  relative  merits  of  some  of  the  less  desirable 
sprays  can  be  described  by  giving  the  percentage  of  spray  injury 
alone.  In  the  case  of  some  of  the  following  mixtures,  therefore,  it 
will  be  the  only  figure  given. 

Plat  3,  iron  Bordeaux  mixture. — This  caused  but  little  more  than 
half  the  injury  of  standard  Bordeaux  mixture.  The  fruit  russeting 
on  the  Ben  Davis  was  marked  40  per  cent. 

Plat  4,  gypsum  Bordeaux  mixture. — This  was  just  about  half  as 
injurious  to  fruit  and  foliage  as  standard  Bordeaux  mixture.  Rus- 
seting on  the  Ben  Davis  was  marked  30  per  cent. 

Plat  5,  neutral  Bordeaux  mixture. — At  first  this  was  not  quite  as 
injurious  as  standard  Bordeaux  mixture,  but  eventually  the  fruit 
russeting  on  the  Ben  Davis  was  so  nearly  the  same  as  to  be  indis- 
tinguishable, and  the  injury  mark  given  was  60  per  cent.  Strange 
to  say,  this  mixture  was  the  only  one  which  seriously  injured  the 
fruit  of  the  York  Imperial,  its  use  resulting  in  20  per  cent  of  injury 
on  that  variety.  It  was  therefore  more  injurious  on  the  whole 
than  standard  Bordeaux  mixture. 

Plat  6,  self-boiled  lime-sulphur. — Fruit  russeting  was  practically 
avoided  by  the  use  of  this  mixture.  There  was  a  mark  of  one-half 
of  1  per  cent  of  russeting  given  to  the  Ben  Davis  fruit.  This  was 
merely  nominal,  however,  and  was  in  the  stem  end  of  the  apples,  prob- 

[Cir.  58] 


i:\im  t:i  mi  \  is  OK    un     \itii.   uiiii    BOM     N  i- u    FUNOICIDl  11 

ably  due  to  water  or  to  the  lead  arsenate.  Noother  russet  injury  to 
fruit  was  noted,  bul  ■  Eev  fungous  spots  were  found  on  the  leaves. 

/'In/  7,  copper-tulphid  mixtun  No.  I.  This  mixture  russeted' the 
fruit  of  the  Ben  Davis  the  least  of  any  copper  spray.  The  mark 
given  was  10  per  cent,  or  one-sixth  of  the  damage  caused  l>\  stand- 
ard Bordeaux  mixture.  On  the  other  hand,  the  leaf  injury  was  only 
l  percent,  so  Blight  as  to  be  scaroerj  noticeable,  and  on  the  Yellow 
Newtown  and  the  fork  [mperial  practically  perfect  marks  were 
given  to  this  mixture.  On  both  leaves  and  fruit  this  mixture  could 
be  need  commercially  under  the  conditions  of  the  past  season  on 
these  varieties,  and  were  it  not  for  the  Blight  russeting  on  the  Hen 
Davis  ii  would  have  ranked  with  the  best  and  had  practically  perfect 
marks  throughout.  Possibly,  by  diluting,  this  injury  could  be  reduced 
still  further. 

/'hit  s,  cojipi r-sul pltiil  miji'iii  Vo.  .'  This  spra)  was  made  with 
the  Btrong  lime-sulphur  solution  instead  of  the  self-boiled  lime- 
sulphur  and  was  inferior  to  the  copper-sulphid  mixture  No.  1. 
The  damage  to  the  fruit  of  the  Hen  Davis,  however,  was  marked  16 
per  cent ,  only  slight  lv  greater,  l>ut  the  foliage  injury  was  quite  serious. 
reaching  lit  per  cent  on  the  Yellow  Newtown.  Substituting  the 
commercial  lime-sulphur  solution  in  making  the  copper  sulphid  in- 
creased the  russeting  from  lo  to  15  per  cent  on  the  fruit  of  the  Ben 
Davis  and  resulted  in  some  considerable  injury  to  the  foliage,  15  per 
cent  on  the  York  Imperial  and  id  per  cent  on  the  Ben  Davis. 

Pint  '■>,  iron-sulp/tiil  mixture. — This  new  fungicide  received  practi- 
cally perfect  marks  both  as  to  fungicidal  action  and  as  to  injury.  In 
the  matter  of  record,  or  percentage  of  spray  injury  and  percentage  of 
fungous  spots,  it  scored  the  highest  mark.  It  has,  however,  a  slight 
physiological  effect  on  the  apple,  which  is  described  Inter,  that  may 
sometimes  be  disadvantageous.  There  was  absolutely  no  injury  in 
the  way  of  russeting  the  fruit  even  on  the  Ben  Davis. 

There  is  a  slight  russeting  around  the  stems  of  apples  in  humid 
climates  that  is  caused  by  water  in  the  form  of  rain  or  dew  in  the 

Cavity.      The   only    apples    free    from    this   Blight    stem    russeting    arc 

those  grown  in  desert  or  dry  countries.  The  stem  russeting  on  the 
iron-sulphid  plat .  however,  was  reduced  to  the  smallest  quantity,  being 
BO  slight  that  it  was  considered  exactly  the  same  as  that  on  unsprayed 
fruits.  There  was  absolutely  no  injury,  and  the  iron  sulphid  pre- 
vented the  fungous  diseases  bo  completely  that  by  close  observation 
only  a  few  spots  could  be  found  on  the  leaves.  \.  mark  of  one-half  <>f 
1  per  cent  for  fungous  injury  was  therefore  given  to  each  variety. 
On  the  fruit  no  spots  were  found  and  ■  perfect  mark  was  given. 

The  fruit  on  the  iron-sulphid  plat  was  slightly  greener  in  appearance 
than  the  unsprayed  fruit,  particularly  toward  the  stem  end.     This 

[Cir      - 


12         EXPERIMENTS   ON    THE   APPLE  WITH   SOME   NEW   FUNGICIDES. 

was  not  so  noticeable  on  the  York  Imperial ;  in  fact,  it  was  scarcely 
apparent  on  that  variety.  On  the  Yellow  Newtown  spraying  with 
copper  sulphid  resulted  in  bright-green  and  apparently  slightly  belated 
fruit  of  such  a  nature  as  probably  not  to  be  objectionable  in  that 
variety.  Although  the  fruit  of  the  Ben  Davis  was  fine  looking,  it  was 
not  quite  so  brilliant  in  appearance  as  that  on  the  lime-sulphur  plat. 
Possibly  it  might  have  improved  by  hanging  on  the  trees  a  week 
longer  and  getting  somewhat  riper. 

On  the  other  hand,  the  foliage  on  the  iron-sulphid  plat  was  hand- 
somer than  that  on  any  of  the  other  plats.  It  was  darker  green  and, 
as  was  afterwards  found,  it  hung  on  longer  than  that  in  any  other 
part  of  the  orchard.  During  the  summer  the  spray  stuck  so  tightly 
and  was  so  abundant  as  to  give  the  trees  a  brownish  appearance,  but 
this  wore  off  at  picking  time,  resulting  in  a  remarkably  fine  dark- 
green  appearance  of  the  leaves.  The  twigs  were  also  more  stocky 
and  the  fruit  buds  plumper  on  these  trees,  although  the  self-boiled 
lime-sulphur  was  a  close  rival  in  this  respect.  This  fine  appearance 
of  the  twigs  and  buds  was  undoubtedly  produced  by  the  excellent 
foliage. 

Plat  10,  arsenate  of  lead  (used  alone). — This  spray  gave  excellent 
results,  not  only  in  its  absence  of  injurious  effects  on  the  foliage  and 
fruit  but  in  preventing  fungous  diseases.  The  injury  was  marked 
zero  throughout.  No  injury  could  be  found  that  was  due  to  spraying 
or  that  was  in  any  way  abnormal.  The  slight  stem  russeting,  as  with 
the  iron  sulphid,  was  considered  natural  Water  russeting.  Further- 
more, the  spraying  seemed  to  protect  the  fruits  from  the  fly-speck, 
the  smut  fungus,  and  the  fruit  spots,  just  as  in  the  case  of  the  other 
mixtures.  On  the  leaves,  however,  a  few  spots  of  cedar  rust  and 
leaf-spot  were  found,  1  per  cent  on  the  Ben  Davis,  1  per  cent  on  the 
Yellow  Newtown,  and  3  per  cent  on  the  York  Imperial. 

On  the  whole,  the  plat  sprayed  with  arsenate  of  lead  compared  very 
favorably  with  the  better  plats.  The  leaves  did  not  have  such  a 
handsome  and  dark-green  appearance  as  those  on  the  iron-sulphid 
plat,  nor  even  as  those  on  the  self-boiled  lime-sulphur  plat.  The 
foliage,  however,  seemed  to  be  perfectly  natural,  making  it  appear 
that  the  extra-good  plats  were  stimulated  by  the  fungicides. 

Plat  11. — No  records  were  taken  of  plat  11,  as  unfortunately  it 
received  by  accident  some  of  the  treatment  with  2-3-50  Bordeaux 
mixture  and  arsenate  of  lead  in  spraying  the  surrounding  orchard. 

Remainder  of  the  orchard. — The  mixture  used  in  the  remainder  of 
the  orchard  was  a  diluted  Bordeaux  mixture,  2-3-50  (2  pounds  of 
bluestone,  3  pounds  of  lime,  and  50  gallons  of  water),  to  which  were 
added  2  pounds  of  arsenate  of  lead.  This  gave  good  results  on  the 
Yellow  Newtown  and  the  York  Imperial,  particularly  on  the  latter 

[Car.  58] 


!  xim.kimi.n  is  OH    rHE  APPLE  WITH  SOME  NEM    FUNGICIDES.        1 .'{ 

variety.  There  was  Borne  leal  injur} .  however,  on  the  York  Imperial 
mid  the  Yellow  Newtown,  becoming  serious  on  man}  of  the  trees.  It 
probably  amounted  t<>  about  one  half  or  two-thirda  of  that  on  the 
■  50  plat.  This  difference  is  attributed  to  the  smaller  amount  <>f 
copper  in  the  mixture  and  to  the  excess  of  lime,  and  possibly  also  to 
the  so  mew  hat  lighter  spraying  used  in  commercial  v.  ork.  The  results 
on  tlic  fruit  were  satisfactory  even  on  these  varieties.  This  was  also 
true  as  to  the  leaves  of  the  Ben  Davis,  the  injur}  Dot  being  very 
serious,  but  the  fruit  of  this  variet}  was  ver}  decidedly  injured  in 
this  orchard,  the  injury  amounting  to  at  least  30  or  possibly  10  per 
cent.  The  possibility  "l"  getting  such  an  injury  on  the  Ben  Davis 
shuts  out  the  use  of  Bordeaux  mixture  on  thai  \  ariety. 

SERIES    ll. 

In  Series  II.  which  contained  only  Ben  Davis  trees,  the  general 
Its  were  exactly  the  same  as  in  Series  I.  Any  differences  were  bo 
alight  as  to  be  attributed  to  accidental  variation.  The  plats  of  four 
tiers  each  of  the  Ben  Davis  carried  heavy  crops  of  fruit,  rendering 
the  difference  in  quality  of  the  fruit  rather  more  emphatic,  perhaps, 
than  in  Serifs  I.  The  foliage  on  these  trees  vvas  somewhat  stronger, 
and  therefore  withstood  the  spray  injury  slightly  better.  Unfortu- 
nately, plats  8  and  9  were  left  out  of  this  serfl 

In  Snies  1 1  i he  same  numbers  were  used  as  in  Series  I  to  designate 
the  plats  sprayed  with  different  mixtures.  All  of  the  plats  receiving 
copper  spray  were  injured  more  or  less.  The  injury  seemed  to  be 
slightly  less,  however,  at  picking  time  than  a  month  before,  as  ti 
Btrong  trees  outgrew  the  russeting  slightly.  On  plat  2,  however, 
where  the  standard  Bordeaux  mixture  was  used,  fruit  russeting 
amounted  to  .">.">  per  cent  on  September  21.  The  trees  Bprayed  with 
the  iron  Bordeaux  and  the  gypsum  Bordeaux  mixtures  were  Blightly 
le-s  ruaseted  than  those  in  Series  1.  Plat  7, sprayed  with  copper sul- 
phid,  gave  a  corresponding  result .  the  injury  being  marked  8  per  cent , 
which  was  the  least  caused  b}  any  copper  spray.  The  self-boiled 
lime-sulphur  gave  the  same  excellent  results.  This  was  also  true  of 
the  arsenate  of  'cad  Used  alone. 

s|   1TI  i  \n   \  I   \l      sKKll  s. 

Tn  the  supplemental  series  in  the  orchard  of  Mr.  Stewart  1V1I,  the 
unsprayed  plat  gave  about  the  same  unfavorable  result  but  was 
quite  so  badly  affected  by  fungous  diseases  as  i    £  I.     The  leaves 

were  marked  50  per  cent  injured  by  fungi,  however,  on  September  8. 
The  «elf-boiled  lime-sulphur  gave  satisfactory  results,  with  no  i 

Beting  whatever,  except   a  trace  at   the  stem  end,  prevent!]  g  the  f 
Bpots   and    the   leaf  spots  and,  with   the  addition  of  the  arsenate  of 

[fir.  B8] 


14        EXPERIMENTS  ON   THE  APPLE   WITH  SOME  NEW   FUNGICIDES. 

lead,  the  greater  part  of  the  insect  injuries.  Of  plat  7,  the  copper- 
sulphid  mixture  gave  the  same  excellent  results  on  the  leaves,  hut 
produced  15  per  cent  of  russeting  on  the  fruit  of  the  Ben  Davis. 

Jn  the  supplemental  test  in  the  orchard  of  Mr.  Phil  Gold,  self- 
boiled  lime-sulphur  was  used  in  comparison  with  standard  Bordeaux 
mixture,  3-5-50.  Plats  2  and  6  were  located  in  an  orchard  which 
had  been  quite  seriously  attacked  by  the  cedar  rust.  The  two 
varieties  York  Imperial  and  Ben  Davis  were  in  alternate  rows  and 
were  included  in  each  plat.  In  the  plat  sprayed  with  Bordeaux  mix- 
ture the  Ben  Davis  trees  showed  15  per  cent  of  injury  to  the  foliage, 
and  the  fruit  was  considerably  russeted.  It  carried  one-half  of  1  per 
cent  of  cedar  rust.  The  York  Imperial  trees  had  about  1 0  per  cent  of 
leaf  injury  from  copper  poisoning  and  had  smooth  fruit,  as  usual, 
but  carried  2}  per  cent  of  cedar  rust.  On  the  plat  sprayed  with 
self-boiled  lime-sulphur,  corresponding  to  plat  6  of  the  main  series, 
there  was  no  spray  injury  to  fruit  or  leaves  of  either  variety,  but 
there  was  a  marked  increase  in  the  cedar  rust,  about  2  per  cent  on 
the  Ben  Davis  and  17  per  cent  on  the  York  Imperial.  Self-boiled 
lime-sulphur,  therefore,  did  not  prove  entirely  successful  in  control- 
ling cedar  rust. 

SUMMARY  OF  RESULTS. 

All  types  of  Bordeaux  mixture  were  injurious.  On  the  Ben  Davis, 
particularly  on  the  fruit,  the  extent  of  this  injury  was  so  great  as  to 
compel  the  abandonment  of  Bordeaux  mixture  for  spraying  this 
variety.  On  the  Yellow  Newtown,  while  the  fruit  suffered  very  much 
less,  the  foliage  suffered  to  a  great  extent,  reaching  a  damage  esti- 
mated at  80  per  cent,  the  highest  percentage  of  injury  produced  by 
an}*  of  the  sprays.  On  the  York  Imperial  the  fruit  was  hurt  but  very 
little  except  with  neutral  Bordeaux  mixture.  With  the  ordinary 
Bordeaux  or  the  modified  Bordeaux  mixtures  the  injury  was  so  slight 
on  this  variety  as  to  be  insignificant  and  was  far  overbalanced  by  the 
benefits.  However,  the  foliage  of  the  York  Imperial  suffered  seriously, 
too  much  to  be  tolerated  if  it  could  possibly  be  avoided.  As  the  York 
Imperial  is  the  most  immune  to  copper  poisoning  of  all  important 
commercial  varieties  as  far  as  fruit  is  concerned,  the  net  result  is  that 
even  on  that  variety,  on  account  of  the  serious  damage  to  foliage, 
Bordeaux  mixture  is  to  be  discarded  if  other  fungicides  can  be  used 
to  do  the  work  without  this  leaf  injury. 

Neutral  Bordeaux  mixture  was  the  worst  form  and  did  more  harm 
than  the  standard  3-3-50  formula,  while  the  2-3-50  formula,  with  its 
excess  of  lime,  was  distinctly  superior  to  the  other  kinds  and  gave 
good  commercial  results  on  the  York  Imperial.  In  blocks  of  the 
York  Imperial  this  2-3-50  Bordeaux  mixture  with  2  pounds  of  arse- 

[Cir.  58] 


EXPERIMENTS  OH    Mir    tf»FLE  WITH  SOME  HB^    PUKOICIDE8. 

nate  of  lead  might  possibly  -^till  be  used,  although  ii  i-  a  little  too 
m\  ere  on  the  lea 

( >n  the  other  hand,  under  the  conditions  obtaining  at  Winchester, 
\  .  and  the  Bame  was  true  al  other  points  in  Virginia  during 
1909,  the  Belf-boiled  lime-sulphur  with  1 1 1 « -  arsenate  of  lead  added 
gave  practically  perfect  commercial  results  <>n  the  fruil  and  entirely 
satisfactory  results  on  the  foliage  except  where  cedar  rusl  was  abnor- 
mally bad,  without  ;tu\  russe ting  or  leaf  injury  whatever.  The  fruil 
Beemed  to  be  even  brighter  and  yellower  than  normal  fruit.  This 
mixture  has  not  proved  to  be  a  verj  powerful  fungicide  for  apple 
diseases  under  extreme  conditions. 

It  should  I).-  noted  thai  Mr.  W.  M.  Scott,  of  the  Bureau  of  Planl 
Industry,  has  developed  the  self-boiled  lime-sulphur  mainly  as  a 
fungicide  for  use  on  the  peach,  for  winch  purpose  it  is  eminently 
successful.  The  down  on  the  peach  skin  serves  admirably  in  retain- 
ing the  mixture  on  the  fruit.  Mr.  Scott  has  also  obtained  some  very 
good  results  on  the  apple  under  favorable  conditions,  bul  has  pointed 
out  that  this  mixture  has  not  given  entirely  satisfactory  results  in  the 
treatment  of  apple  BCab  under  extreme  conditions.  In  the  experi- 
ments on  pecan  scab  carried  on  by  the  writer  during  the  lasl  year  in 
South  Carolina,  where  beavj  and  frequenl  rains  occurred,  self-boiled 
lime-sulphur  failed  in  preventing  the  attacks  of  this  fungus. 

The  Belf-boiled  lime-sulphur  does  not  appear  to  withstand  heavy 
w  ashing  rains.  This  throws  some  doubl  on  the  ability  of  the  straight 
Belf-boiled  lime-sulphur  to  protect  against  the  attack  of  fungous 
diseases  under  varied  and  unfavorable  conditions. 

It  should  be  noted  that  the  sdf-hoiled  liine-sulphur  permitted 
2  percent  of  infection  on  the  leaves  of  the  Ben  Davis,  •'!  per  cent 
on  the  fellow  Newtown,  and  1  per  cent  on  the  York  Imperial  in 
Series  I.  While  this  amount  of  fungous  disease  on  the  leaves  is 
insignificant,  nevertheless,  it  was  the  highest  obtained  in  any  of  the 
plats  of  this  series.  It  therefore  brings  out  the  doubt  as  to  the 
fungicidal  strength  of  this  otherwise  remarkably  good  mixture. 

The  new  form  of  iron  sulphid  gave  practically  perfect  results  on 
both  leaves  and  fruit  of  all  varieties.  It  was  absolutely  aoninjurious. 
Furthermore,  it  gave  the  most  perfect  protection  from  fungi,  the  fruit 
having  no  infection  whatever-  and  the  leaves  being  given  a  mark  of 
one-half  of  l  per  cent  of  fungous  injury  on  all  varieties.  The  foliage  on 
this  plat  had  a.  part  icularlv  line  dark-green  color  and  held  on  later  than 
any  other  leaves  in  the  orchard.  The  twigs  were  stockier  and  the 
buds  were  liner  and  plumper  than  on  any  other-  plat,  although  the 
self-boiled  lime-sulphur  plat  was  a  cl<  >nd  in  this  regard.     It 

should  be  noted,  however,  that  the  fruit  was  slightly  greener  in  color 
and  apparently  a  little  later  in  ripening  than  on  the  other  pis 
[Or.  ."s| 


16        EXPERIMENTS  ON  THE  APPLE  WITH  SOME  NEW  FUNGICIDES. 

particularly  t lie  lime-sulphur  plat,  its  real  competitor  in  efficiency. 
In  the  case  of  the  Yellow  Newtown,  the  slightly  greener  color  might 
not  he  ohjectionahle.  With  the  York  Imperial  it  was  not  sufficiently 
marked  to  be  important.  On  the  Ben  Davis  it  might  possibly  be 
slightly  objectionable,  unless  by  allowing  the  fruit  to  hang  later  it 
eventually  attained  full  color. 

On  plat  7  the  new  form  of  copper  sulphid  gave  entirely  satisfactory 
results  on  both  fruit  and  foliage  of  the  Yellow  Newtown  and  the  York 
Imperial  varieties.  It  gave  excellent  results  on  the  foliage  of  the 
Ben  Davis,  but  russeted  the  fruit  about  10  per  cent — that  is,  one-sixth 
as  much  as  standard  Bordeaux  mixture.  Under  the  conditions  at 
"Winchester  the  new  copper  sulphid  was  almost,  if  not  quite,  abso- 
lutely harmless  on  the  Yellow  Newtown  and  the  York  Imperial,  and 
this  is  the  only  copper  spray  of  which  this  could  be  said.  If  these 
results  can  be  depended  upon  in  the  future,  this  spray  could  be  used 
commercially  with  excellent  success.  The  10  per  cent  of  russeting  of 
the  Ben  Davis  would  entirely  prohibit  its  use  on  that  variety  if  the 
self-boiled  lime-sulphur  and  the  iron  sulphid  prove  as  efficient  as 
indicated  by  this  experiment.  The  percentage  of  russeting  on  the 
Ben  Davis  might  possibly  be  reduced  by  cutting  down  the  amount 
of  copper  from  2  pounds  to  1  pound,  or  even  to  one-half  pound.  Fur- 
thermore, this  copper  sulphid  may  prove  to  be  noninjurious  on  the 
Ben  Davis  fruit  after  it  has  reached  a  certain  stage  of  growth.  We 
may  say,  therefore,  that  we  have  in  the  copper  sulphid  the  least 
injurious  form  of  copper,  and  if  copper  is  absolutely  necessary  for 
ultimate  success  in  controlling  the  most  difficult  diseases,  this  form 
of  spray  produces  the  minimum  amount  of  injury. 

One  of  the  surprises  of  this  experiment  was  the  remarkably  good 
result  obtained  from  the  arsenate  of  lead  plat,  it  showing  entire 
freedom  from  russet  injury.  Under  the  rather  easy  conditions  in 
regard  to  fungous  infection  prevailing  at  Winchester  during  the 
season  in  question  arsenate  of  lead  proved  efficacious  in  preventing 
fungous  diseases.  It  is  certain  that  under  more  adverse  conditions 
this  freedom  from  fungi  can  not  be  depended  upon  to  the  extent 
indicated  in  these  experiments. 

The  efficiency  of  the  arsenate  of  lead  cast  some  doubt  as  to  whether 
it  was  not  concerned  in  the  success  of  the  self-boiled  lime-sulphur 
and  the  iron-sulphid  plats,  and  perhaps  some  of  the  others,  since  it 
was  added  to  all  of  the  mixtures  used.  Self-boiled  lime-sulphur, 
however,  has  been  successful  in  several  of  Mr.  Scott's  experiments  on 
the  apple,  and  still  more  so  on  the  peach,  and  it  is  now  recognized 
as  the  standard  fungicide  for  the  summer  treatment  of  peach  diseases. 
An  iron  sulphid  somewhat  similar  to  this  one,  made  with  the  sulphur 
solution,  in  the  experiments  of  Mr.  W.  II.  Volck,  at  Watsonville, 
Cal.,  on  the  powdery  mildew  of  the  apple,  proved  superior  to  Bor- 

[Cir.  58] 


EXPERIMENTS  ON    Mil      W'IM.I.    Willi    SOME    NEM     FUNGICIDES. 


17 


deaiui   mixture.     Possiblj    this  form  of  iron  Bulphid   ma}    | 
superiority  in  t  lie  case  "f  certain  other  fun 

It  is,  however,  not  considered  Bafe  i>»  recommend  either  the  iron- 
Bulphid  or  the  copper-sulphid  Bpra)  for  general  commercial  use  until 
the)  have  been  further  tested.  It  is  quite  possible  thai  differenl 
dilutions  ma)  be  found  desirable.  Perhaps  the  Belf-boiled  lime- 
sulphur  niav  be  reenforced  in  its  fungicidal  properties  l>\  adding 
just  a  little  bluestone,  say  I  }  »•  n  1 1 1 . 1  or  even  half  a  pound  per 
barrel.  It  would  thus  be  a  very  dilute  copper  sulphid  with  an  excess 
of  Belf-boiled  lime-sulphur.  Ii  is  possible  thai  the  amount  of  cop- 
per sulphate  added  mighl  be  adjusted  tosuil  the  susceptibility  of  the 
differenl  varieties.  The  full  amount  2  pounds  could  be  added 
for  the  Yellow  Newtown,  York  Imperial,  and  probabl)  some  other 
varieties,  while  the  minimum  amount  of  I  pound  or  perhaps  even 
half  a  pound  could  be  added  for  the  Hen  Davis. 

The  iron  Bulphid  made  with  the  Belf-boiled  lime-sulphur  as  a  basis 
sticks  so  much  better  than  self-boiled  lime-sulphur  and  in  the  test 
above  described  was  bo  successful  that  it  Beems  very  promising.  It 
i^  capable  of  endless  modification.  Perhaps  a  -mailer  quantity  than 
the  .'5  pounds  used  in  the  experiment  could  be  added  to  the  barrel 
of  10-10  .")()  or  s  s  ")0  silf-hoik'd  lime-sulphur  with  beneficial  results. 
This  may  serve  as  a  sticker  for  the  self-boiled  lime-sulphur  mixture 
and  increase  its  fungicidal  power-.  It  may  permit  the  use  of  an 
even  more  dilute  form  of  the  self-boiled  lime-sulphur  than  the  s  s-50 
formula  which  is  now  recommended  for  commercial  preparations. 

There  i-  a  possibility  of  combining  the  two  mixture-  of  iron  sulphid 
and  copper  sulphid  in  various  preparations  for  those  fungous  diseases 
or  combinations  of  fungous  diseases  that  occur.  For  instance,  if 
the  cedar  rust  requires  copper  for  it-  control  it  may  be  preferred  to 
add  a  little  copper  to  the  iron-sulphid  mixture.  It  is  evident  that 
considerable  experimenting  will  he  needed  to  settle  these  questions. 

The  harmle.-s  character  of  the  iron  sulphid  is  believed  to  he  pretty 
well  shown.  It  will  require  tests  under  severe  outbreaks  of  fungous 
diseases  before  its  fungicidal  powers  can  he  properly  determined, 
however.  The  iron  sulphid  or  even  the  copper  sulphid  will  not  be 
immended  for  commercial  work  until  further  tested.  They 
should  he  tried,  if  at  all,  in  experiments  in  a  small  way.  Mr.  Scott 
has  shown  that  the  commercial  lime-sulphur  solution  diluted  to  1A 
gallons  per  50  gallons  of  water  i-  a  more  powerful  fungicide  than  the 
Belf-boiled  lime-sulphur  preparation  and  i-  perfectly  safe  at  that 
strength  on  the  apple.  This  mixture  i-  therefore  recommended  in 
Bpraying  the  apple  and  i-  available  for  those  cases  where  apple  scab 
or  some  other  serious  disease  i-  feared  and  a  stronger  fungicide  than 
Belf-boiled  lime  sulphur  is  desired. 

[Clr.  58] 


18        EXPERIMENTS  ON   THE  APPLE   WITH   SOME   NEW    FUNGICIDES. 

Where  a  dangerous  outbreak  of  bitter-rot  occurs  late  in  the  season, 
probably,  with  our  present  knowledge  of  the  subject,  a  moderately 
strong  Bordeaux  mixture — say  4-4-50— would  still  be  the  safest 
thing  to  recommend  for  use. 

CONCLUSIONS. 

All  the  fungicides  containing  copper  used  in  the  tests  here  reported 
upon  russeted  the  fruit  of  the  Ben  Davis  apple  seriously,  injuring  it 
from  10  to  60  per  cent. 

The  copper-sulphid  preparation  made  from  self-boiled  lime-sulphur 
was  the  least  injurious  copper  spray,  causing  only  10  per  cent  of 
injury  to  the  fruit  of  the  Ben  Davis  trees. 

Neutral  Bordeaux  mixture  proved  the  worst  spray  mixture  used, 
even  injuring  the  fruit  of  the  York  Imperial.  An  excess  of  lime, 
therefore,  is  an  advantage  in  tending  to  render  Bordeaux  mixture 
harmless. 

Standard  Bordeaux  mixture,  3-3-50,  was  the  next  to  the  worst 
mixture  for  spray  injury,  giving  60  per  cent  of  injury  on  the  Ben 
Davis  fruits.  Cutting  down  the  quantity  of  copper  sulphate  in 
Bordeaux  mixture  from  3  to  2  pounds  reduced  the  injury,  but  did 
not  prevent  it. 

Copper  poisoning  occurs  seriously  on  the  leaves,  even  damaging 
them  to  a  greater  extent  than  the  fruit,  reaching  80  per  cent  on  the 
Yellow  Newtown  when  Bordeaux  mixture  is  used. 

The  susceptibility  of  the  leaves  to  copper  poisoning  bears  no  direct 
relation  to  the  behavior  of  the  fruit  in  this  regard.  The  leaves  of 
any  variety  may  be  badly  injured  while  the  fruit  is  not  hurt,  or  vice 
versa. 

Adding  certain  materials,  such  as  gypsum,  iron  sulphate,  lime- 
sulphur  solution,  etc.,  to  Bordeaux  mixture  in  all  cases  reduced  the 
injury,  but  did  not  entirely  prevent  it  except  in  the  case  of  the 
solf-boiled  lime-sulphur  in  part,  where  a  new  compound  was 
formed. 

A  new  form  of  copper  sulphid  was  made,  the  self-boiled  lime- 
sulphur  being  used  as  a  basis,  and  tested  for  the  first  time,  proving 
effective  and  almost  completely  noninjurious  except  to  the  fruit  of 
the  Ben  Davis  variety. 

A  similar  fungicide  made  with  the  commercial  lime-sulphur  solu- 
tion was  only  slightly  more  injurious  to  the  fruit,  but  was  distinctly 
injurious  to  the  foliage. 

A  new  iron-sulphid  fungicide  was  made  and  tested  for  the  first 
time.  It  was  entirely  harmless  and  gave  remarkably  good  results 
under  the  conditions  at  "Winchester,  Va.,  in  1909,  except  that  it 
produced  distinctly  greener  fruits.  It  ma}-  therefore  be  regarded  as 
promising. 

[Cir.  58] 


I  AIM   II!  \l  I    \  IS    (IN      I  III      AIMM.K     Willi     BOMB     N  I  .  \\      FUNGICIDES.  1  1 1 

Arsenate  of  lead,  2  pounds  to  the  barrel,  can  be  used  in  anj  of  the 
mixtures  tested.     When  used  alone  this  insecticide  seemed  to  p< 
considerable  fungicidal  value,  though  probabrj  nol  enough  to  be  de- 
pended upon  for  genera]  use. 

Approved : 

James  Wilson, 

n<  en  tary  <<1  Agricuttun  . 


Washington,  D.  ('..  March  W,  1910. 

[Clr  58] 


UNIVERSITY  OF  FLORIDA 


3  1262  08928  9770 


